Thermal regulation of an ion implantation system

Abstract

A thermoregulation system for an ion implantation system to reduce the temperature in the ion implanter and components therein, or attached thereto, to a temperature at which an ion source material, used in the ion implanter, has a vapor pressure that yields a reduced concentration of vapors. Such arrangement markedly reduces the risk of exposure to harmful vapors from the ion source material.

Description

[0002] 1. Field of the Invention[0003] The present invention relates to an ion implantation system, and more particularly, to thermal regulation of an ion implantation system to reduce the temperature therein and to minimize the risk of exposure to harmful vapors.[0004] 2. Description of the Related Art[0005] Numerous semiconductor manufacturing processes employ ion implantation for forming a p-n junction by adding dopants (impurities), such as boron (B) and phosphorus (P) to a semiconductor substrate. Ion implantation makes it possible to accurately control the concentration and depth of impurities to be diffused into a target spot on the semiconductor substrate.[0006] Typically, an ion implanter includes an ion source that ionizes an atom or molecule of the material to be implanted. The generated ions are accelerated to form an ion beam that is directed toward a target, such as a silicon chip or wafer, and impacts a desired area or pattern on the target. The entire operation is ca...

AI Technical Summary

Problems solved by technology

As such, these smaller and thinner requirements challenge the ability of present systems to produce high dose ion beams with the low energy required to implant a high concentration of ions at a shallow depth in the semiconductor device

However, low energy ion beams are used for shallow implants, but, for standard dopant atomic ions at low beam energies, ion current is constrained by physics limitations associated with extraction and transport losses

However, as beam energy decreases to accommodate thinner devices, beam transport of standard ions, defined as dopants, such as boron (B.sup.+), arsenic (As.sup.+) and phosphorus (P.sup.+), becomes inefficient due to beam space charge.

However, the use of heavy molecular ions, such as decaborane, creates some unique health and safety challenges.

For example, the vapor pressure of decaborane is low at room temperature (at the threshold limit value), and can be hazardous at modestly elevated temperatures.

Due to the high cost of owning an ion implant system and the need to minimize down time, sources are frequently removed at temperatures significantly above room temperature.

Toxic solids with thermally sensitive vapor pressure, like decaborane, are not routinely u

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